The present invention relates to a dual-cannister inhaler for effectively delivering medications by inhalation through the mouth of patients having a spacer for more effectively mixing the medication and air, and an easy to operate lever mechanism.
Inhalation into the lungs of a patient of a metered dose of medication is an increasingly common delivery system for a variety of drugs, including but not limited in any way to anti-asthma medications, insulin (See http.//www.msnbc.com/news/52508.asp), various steroids and treatments specific to various pulmonary diseases. One concern with metered dose inhalers or aerosol pressurized cartridges has been that, while the metered dose inhaler canister dispenses a fixed, metered dose of medication, not all of the metered dose actually reaches the lungs of the patient. Even if a patient times inhalation with the dispersal of the medication from the metered dose inhaler (MDI), the amount of medication reaching the lungs is inconsistent, depending on how much of the medication is dissolved and entrained in the stream of air entering the patient""s lungs, and how much of the medication is deposited on surfaces of the inhalation apparatus, the mouth and oropharyngeal area of the patient. Furthermore, deposits in the mouth and oropharyngeal area of the patient can cause complications, such as candidiasis, as well as leave an unpleasant aftertaste. In addition, many patients using inhalation devices have practical problems with the use of typical inhalers, including difficulty with compressing the metered dose inhaler canister, problems timing inhalation with the dispersal of medication, and inability to inhale the complete dose of medication in a single breath, particularly young, elderly, or patients who suffer from asthma and dysphonia or thrush from inhaled corticosteroids. In practice, it is common to see patients activating their metered dose inhalers multiple times, although the metered dose should have been dispensed in a single activation. This is a typical response of patients to the difficulty and inconsistency of medication delivery, undermining the effectiveness of the MDI, which can lead to over-medication, under-medication, or waste and higher than necessary costs for treatment.
The typical solution to the problem of inconsistent medication delivery has been to provide a xe2x80x9cspacerxe2x80x9d or xe2x80x9cchamberxe2x80x9d within the inhalation device. A spacer or chamber is merely a reservoir of air. The metered dose of medication, usually an atomized mist or vapor, mixes with the reservoir of air before being inhaled by the patient, reducing the inconsistency of delivery due to timing difficulties. See U.S. Pat. Nos. 4,470,412; 4,790,305; 4,926,852; 5,012,803; 5,040,527; 5,042,467; 5,816,240; and 6,026,807. An additional improvement incorporated into many of the devices with spacers has been a simple valve mechanism to allow the patient to inhale the medication in more than one breath. For example, see U.S. Pat. Nos. 4,470,412; 5,385,140. The efficacy of such devices for correcting errors in patient technique has been shown in general medical research. For example, see Demirkan, et al., xe2x80x9cSalmeterol Administration by Metered-Dose Inhaler Alone vs. Metered-Dose Inhaler Plus Valved Holding Chamber,xe2x80x9d Chest 117 (2000) pp. 1314-1318, Finlay and Zuberbuhler, xe2x80x9cIn vitro comparison of beclomethasone and salbutamol metered-dose inhaler aerosols inhaled during pediatric tidal breathing from four valved holding chambers,xe2x80x9d Chest 114 (1998) pp. 1676-1680, and Konig, xe2x80x9cSpacer devices used with metered-dose inhalers. Breakthrough or gimmick?xe2x80x9d Chest 88 (1985) pp. 276-284.
One problem not generally addressed is the ease of compression of MDI canisters. One spacer, called the EZ Spacer(copyright), http://www.weez.com, improves the ease of compression by allowing the patient or another to use both thumbs on a pull handle and the forefingers on the MDI canister, but this is only a marginal improvement over the standard design, allowing merely one thumb and forefinger for compression of the MDI, and is no aid to patients who do not have full use of both of their thumbs and forefingers.
For infants or other patients who have difficulty using a mouthpiece, a mask is commonly attached or incorporated onto the MDI inhaler. See U.S. Pat. Nos. 4,809,692; 4,832,015; 5,012,804; 5,427,089; 5,645,049; 5,988,160. Also, some devices include an audible signaling device to warn patients when inhalation exceeds a desirable rate. For example, see U.S. Pat. Nos. 4,809,692 and 5,042,467.
One method of attaching a spacer to the MDI cannister is to insert the MDI inhaler into a universal adapter such as shown in U.S. Pat. No. 5,848,588, but this is bulky and awkward to use, and does nothing to ease the difficulty of compressing the MDI canister for infirm or ailing patients. Other devices are designed to have a specific MDI canister inserted into the device. It would be beneficial to be able to insert MDI canisters for various medications into an inhaler with a universal receptor.
The present invention is directed to an inhaler that has universal receptors for multiple medication canisters 10, 11 or metered dose inhaler (MDI) canisters, also referred to as cartridges. One typical embodiment of the invention accepts two canisters (dual canisters), and has a lever arm 22 that is easy to depress, a chamber 24 that acts as a spacer, and a mouthpiece 25, having an optional valve mechanism 62 and over-pressure whistle 63, that improves the efficiency of medication delivery, and a slidable selector switch 21 that permits the user to select the mode of operation. The modes of operation include selecting either of the two canisters individually. An additional non-operational setting locks the actuator lever 23 to prevent inadvertent dispensing of medication during periods of non-use.
One object of the invention benefits patients who are infirm or young, by reducing the difficulty in using an inhalation device. The actuator lever 23 allows the entire hand to be used in depressing the MDI canister, and also provides a mechanical advantage, reducing the pressure necessary to dispense the medication. The sliding selector switch 21 is easy to manipulate, and can be put into position to operate either of the dual canisters individually with one hand. The optional locking position can also be selected by a patient with only one hand. An optional indicator shows which of the two canisters is selected by the sliding selector switch.
In a preferred embodiment of the multi-canister inhaler, the dual canister design allows two different kinds of medication to be dispensed by a single inhaler. Increasingly, patients require multiple MDI medications, and the use of a single inhaler for two different medications, which reside conveniently within the inhaler, reduces problems with storage, retrieval, and insertion of MDI canisters into the inhaler for those that are infirm, young or in distress. Alternatively, the second canister may be inserted as a reserve supply for those patients that require assistance with insertion of canisters into an inhalation device, allowing the patient to switch to the reserve supply by merely pushing the sliding selector switch.
In one embodiment, the standard, universal cowling is designed to accept MDI canisters of nearly all commonly prescribed medications, and the cowling helps to guide the canister into the inlet port of the housing when the patient inserts a MDI canister into the inhaler. In addition, the cowling provides support to the canister when the patient depresses the actuator lever, dispensing medication into the housing of the inhaler. Specialized cowlings may be designed for unusual MDI canisters or new MDI canisters that would not fit the universal cowling. By universal, the inventors mean that the cowling is designed to accept nearly all commonly prescribed MDI canisters.
Upon dispensing the medication, the atomized mist from the inhaler is directed through the housing and into the chamber. During inhalation by the patient, a vent in the housing brings fresh air into the housing sweeping the remaining atomized mist from the housing into the chamber, where it mixes with the air, and is drawn into the patients lungs through the patients mouth. In one preferred embodiment of the invention a valve assembly in the mouthpiece of the chamber allows the mixture of medication and air to be drawn through the mouthpiece during inhalation, see FIG. 8, for example, but during exhalation, the inhalation valve closes, and an exhalation valve opens, allowing the exhaled air to escape from an exhalation vent in the mouthpiece. This allows the patient to inhale the medication in multiple breaths.
It should be obvious to one of ordinary skill in the art that an inhaler with access ports for more than two canisters could be configured in the same way as the dual canister design shown in the figures, and presented in the detailed description of the invention. Indeed, the invention is not limited to a dual canister design, but would include a multiple canister design, which includes a sliding selector switch able to engage each of the multiple MDI canisters inserted into an expanded cowling.